The present invention relates generally to bioactive liposomes suitable for delivery to tissues and to a method for their production and, more specifically, to positively charged liposomes useful as carriers of lipophilic molecules and particularly for application to deliver lipophilic molecules, such as carotenoids, via iontophoresis to ocular tissues using iontophoresis.
Lutein is associated with reducing the risk of developing AMD (age-related macular degeneration) and cataracts extraction due to its antioxidant and photoprotective effects, and its exclusive distribution in the eye macula [Kijlstra A., Tian Y., Kelly E. R., Berendschot T. T. 2012. Lutein: more than just a filter for blue light. Prog Retin Eye Res. 31:303-315]. Lutein has been widely used through oral supplementation with the rationale that systemic circulation can bring lutein to the coroidal circulation for uptake into the macula, through xanthophyll-binding protein [Yemelyanov A. Y., Katz N. B., Bernstein P. S. 2001. Ligand-binding characterization of xanthophyll carotenoids to solubilized membrane proteins derived from human retina. Exp Eye Res. 72:381-392]. However, several reports demonstrate that only a small percentage of lutein reaches the macula [Bone R. A., Landrum J. T., Guerra L. H., Ruiz C. A. 2003. Lutein and zeaxanthin dietary supplements raise macular pigment density and serum concentrations of these carotenoids in humans. J Nutr. 133:992-998; Landrum J. T., Bone R. A., Joa H., Kilburn M. D., Moore L. L., Sprague K. E. 1997. A one year study of the macular pigment: the effect of 140 days of a lutein supplement. Exp Eye Res. 65:57-62; Ma L., Lin X. M. 2010. Effects of lutein and zeaxanthin on aspects of eye health. J Sci Food Agric. 90:2-12]. Moreover, due to eye barrier limits, therapeutic treatments in the posterior eye segment are difficult. Since the eye is protected by the tear film, corneal, vitreous, blood-retinal and blood-aqueous barriers it is very difficult to deliver drugs to the eye, particularly to the retina, in sufficient concentrations and with minimal side-effects [Barar J., Javadzadeh A. R., Omidi Y. 2008. Ocular novel drug delivery: impacts of membranes and barriers. Expert Opin Drug Deliv. 5:567-581; de la Fuente M., Ravina M., Paolicelli P., Sanchez A., Seijo B., Alonso M. J. 2010. Chitosan-based nanostructures: a delivery platform for ocular therapeutics. Adv Drug Deliv Rev. 62:100-117]. In-situ applications have been used to overcome this problem; however, slow delivery systems such as implants are very invasive and expensive. Recently, intra-vitreous injections of lutein/zeaxanthin have been used to stain specific preretinal membranes and other eye structures [Sousa-Martins D., Maia M., Moraes M., Lima-Filho A. A., Rodrigues E. B., Chen J., Farah M. E., Santos L. B., Belfort R., Jr. 2012. Use of lutein and zeaxanthin alone or combined with Brilliant Blue to identify intraocular structures intraoperatively. Retina. 32:1328-1336; Rodrigues E. B., Costa E. F., Penha F. M., Melo G. B., Bottos J., Dib E., Furlani B., Lima V. C., Maia M., Meyer C. H., Hofling-Lima A. L., Farah M. E. 2009. The use of vital dyes in ocular surgery. Surv Ophthalmol. 54:576-617; Maia M., Furlani B. A., Souza-Lima A. A., Martins D. S., Navarro R. M., Belfort R., Jr. 2014. Lutein: a new dye for chromovitrectomy. Retina. 34:262-272; Badaro E., Furlani B., Prazeres J., Maia M., Lima A. A., Souza-Martins D., Muccioli C., Lucatto L. F., Belfort R., Jr. 2014. Soluble lutein in combination with brilliant blue as a new dye for chromovitrectomy. Graefes Arch Clin Exp Ophthalmol. 252:1071-1078]. This has been the first data on in-situ delivery of lutein towards the macula, exploiting lutein's intrinsic staining effect. Lutein/zeaxanthin potential in delaying AMD progression and potential neuroprotective action shown in different trials has not yet been proven through in-situ application following intraocular delivery. Intra-vitreous injection of lutein with a prevention purpose may be a too invasive way of delivering lutein towards the macula, with the disadvantage of poor patient acceptance.
Iontophoresis is a technology that uses controlled low-level electrical energy to transport ionized drugs through a biological membrane [Eljarrat-Binstock E., Domb A. J. 2006. Iontophoresis: a non-invasive ocular drug delivery. J Control Release. 110:479-489]. Different iontophoresis delivery systems for ophthalmic use have been created and have been used to safely and effectively deliver medication to both the anterior and posterior segments of the human eye [Eljarrat-Binstock E., Domb A. J. 2006. Iontophoresis: a non-invasive ocular drug delivery. J Control Release. 110:479-489]. With this technology it is possible to delivery significant amounts of macromolecules across the cornea and sclera. What is needed is a novel, stable form of lutein/zeaxanthin that is charged, so the iontophoresis device can propel high concentrations of the charged lutein/zeaxanthin particles transclerally or/and transcorneally. Other lipophilic substances, such as carotenoids, anti-inflammatory molecules or anti-angiogenic compounds, may also be delivered to the eye by iontophoresis using the same vehicle described herein.